Letter

Reabsorption of self-generated turbulent energy by pick-up protons in the outer heliosphere

S. V. Chalov1, D. B. Alexashov1 and H. J. Fahr2

1
Institute for Problems in Mechanics of the Russian
Academy of Sciences, Pr. Vernadskogo 101-1, 119526 Moscow, Russia
2
Institute for Astrophysics and Extraterrestrial Research of
the University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany

(Received 5 January 2004 / Accepted 11 February 2004)

Abstract It is well known that newly created pick-up ions are
first injected into a toroidal distribution in the velocity space
which comoves with the solar wind. This distribution is, however,
unstable with respect to excitation of resonant MHD waves, and
thus by wave-driving some specific amount of the initial kinetic
energy of pick-up ions is handed over to the ambient wave fields,
while the pick-up ion velocity distribution thereby is rearranged.
In this paper we describe the developement of the wavenumber
spectrum of pick-up proton-generated turbulence and the pick-up
proton energy spectrum resulting from resonant reabsorption of
this turbulence, by solving simultaneously the coupled system of
two differential equations for the spectral turbulence power and
the pick-up proton spectral intensity. We show that the majority
of pick-up generated wave energy in the range of wavenumbers above
the wavenumber at which the waves are produced is reabsorbed by
the pick-up protons themselves.